Ignoring the lack of updates if the game is buggy, games back then were also more focused on quality and make gamers replay the game with unlockable features based on skills, not money. I can't count the number of times I played Metal Gear Solid games over and over to unlock new features playing the hardest difficulty and with handicap features, and also to find Easter eggs. Speaking of Easter eggs, you'd lose a number of hours exploring every nook and cranny finding them!
Have you ever noticed that almost all of the retro games worth playing happen to be the ones you played back in the day? But the games you didn't play don't hold up? What a crazy coincidence.
Game design is better today than it has ever been, and it keeps improving. All those old mechanics still exist. You just don't have to slog through hours of bullshit to get to them anymore. Unless that's what you want, in which case that is also available.
If you want a manual, play Tunic. If you want punishing difficulty, play Hollow Knight. If you want to delve into new games with unknown mechanics that you figure out as you go, play UFO 50. There are so many options, and you never need to see a microtransaction unless you want to.